The present invention relates to refractory assemblies employed in a slide gate or sliding closure unit for controlling the discharge of molten metal from a metallurgical vessel. Particularly, the present invention relates to such an assembly for use as a stationary plate assembly or as a slidable plate assembly and including a refractory plate having therethrough at least one discharge opening and having a sliding surface, with a metal sheath mounted exteriorly of the refractory plate.
One known refractory plate assembly of this type is disclosed in DE-PS 38 05 074, corresponding to U.S. Pat. No. 5,074,442. Such known assembly includes a metal sheath that extends in a direction away from the sliding surface to a position to be level with the opposite side of the refractory plate, i.e. to be level with that portion of the refractory plate that confronts a refractory sleeve of the sliding closure unit to define therewith a joint. In other words, that end of the metal sheath is flush with the respective end or portion of the refractory plate opposite to the sliding surface thereof. The joint between the refractory sleeve and this end or portion of the refractory plate is from 3 to 5 mm. To provide a seal of this joint between the refractory plate and the refractory sleeve, there is provided in the joint a commercially available refractory material, for example a refractory mortar. In practical operation however it can occur that the mortar is not perfectly distributed over the entire joint or it can occur that the sleeve is spaced too far from the plate, such that there is too little mortar to fill the joint. As a result, the joint is not satisfactorily sealed around the passage defined by discharge openings through the sleeve and plate. In the worst case, this condition can lead to so-called molten metal breakthrough, i.e. where molten metal passes laterally through the joint, thus flowing out between the sleeve and the plate. This can lead to total destruction of the sliding closure unit.